Research uncovers new depths to dolphin sociology

Recent research on how dolphins interact with one another has shown surprising levels of complexity. Groups of dolphins have been observed working together and dolphins of different species may even be able to communicate – or at least attempt to.

Science NOW reported on two dolphin papers showing social co-operation, while the BBC covered preliminary research on dolphin communication.

Bottlenose dolphin males often team up in groups of two or three in order to mate with females. Sometimes other duos or trios will try to steal the female from them, so the dolphins are known to join together with other duos or trios in order to keep the females. It's now been found that, in the largest fights, even those groups may receive assistance from other groups of male dolphins. This is the most complex social interaction observed in non-humans and may help to explain dolphin intelligence.

The second paper reported on by Science NOW found that female dolphins also form groups, and can raise more calves if they are friends with dolphins who have raised calves to maturity (3-years-old).

The BBC reported on a paper covering the interaction between two species of dolphins – Bottlenose and Guyana/Costero – living off Costa Rica. The Bottlenose dolphins are larger and communicate with deeper calls than Guyana dolphins. When they are together, they change to using an intermediate call. Due to technical restraints it is not known whether both species are modifying their calls or only one.

As Bottlenose dolphins are known to harass the Guyana dolphins, it may be that the Guyana dolphins are attempting to use a threatening Bottlenose communication to deter them. However Dr May-Collado was quoted saying, "I wouldn't be surprised that they can modify their signals to mimic, and even possibly communicate with other species."

Although not related to their sociology, a new species of dolphin which lived between two and three million years ago has also been discovered.